1. Field of the Invention
The present invention relates to a device for adjusting the width of a paper web after being printed on by at least one printing unit in a rotary lithographic press for printing on the paper web in an overlaid manner using a plurality of printing units. In particular, the present invention relates to a paper web width adjustment device for adjusting the width of a paper web by enabling an appropriate number of pressing members provided appropriately in a rotatable manner to be moved towards and away from the surface of the paper web so as to press against the surface of the paper web, deciding upon an appropriate position and then causing a ripple in the paper web.
2. Description of Related Art
In lithographic printing using dampening water, when the paper web passes through a printing unit, an image is printed and dampening water is provided via the non-image area parts. During this time, the pulp fiber of the paper web absorbs the dampening water and swells in the radial direction of the fiber so that the width of the paper web is enlarged.
Because of this, as shown, for example, in FIG. 6, with overlaid printing using a rotary lithographic press TP, there is a problem that mismatching occurs due to enlarging of the width of the paper web W between an image printed previously and an image printed later.
In order to resolve this problem the applicant proposed Japanese Patent Laid-open Publication No. Hei. 5-178511 (related art 1). In related art 1, as a xe2x80x9cweb paper width adjustment device, web paper width adjustment method, and a rotary lithographic press having the web paper width adjustment devicexe2x80x9d, technology is disclosed for adjusting the width of a paper web by providing rotatable pressing members between the printing units facing both surfaces of the paper web and moving the pressing members towards and away from the surfaces of the paper web, having the pressing members come into contact with the surfaces of the paper web and having the pressing members press the paper web while rotating in the direction of travel of the paper web so as to generate a ripple in the paper web.
The paper web width adjustment device of related art 1 comprises a plurality of pressing members provided in the widthwise direction of the paper web so as to be rotatable while making contact with the traveling paper web and being provided alternately on both sides of the paper web so as to sandwich the paper web, shafts provided side by side so as to pass through the pressing members on each side of the paper web and be rotatable and supported about the same central line, eccentric sleeves provided so as to be fixed at both ends of each shaft so as to be capable of being angularly displaced about a common central line differing from the central lines, gears provided so as to engage with gears of the shafts provided side by side in an angularly displaceable manner so as to be integral with the eccentric sleeves and be fitted to each of the eccentric sleeves, and a drive source for driving each of the gears.
The paper web width adjustment device of related art 1 transmits drive using the drive source, causes the eccentric sleeves to be displaced angularly due to angular displacement of the gears, and the plurality of pressing members supported in a rotatable manner on the shafts fitted at a position eccentric with respect to the central lines of the eccentric sleeves are made to move about the central lines of the eccentric sleeves so as to move towards and away from the surface of the paper web.
In an embodiment of a paper web width adjustment device of related art 1, pressing surfaces 1 pressing web paper W traveling towards the print unit P are made to face both surfaces of the web paper W. The pressing surface 1 facing one surface of the web paper W and the pressing surface 1 facing the other surface of the web paper W are placed alternately along the widthwise direction of the web paper W. Pressing surfaces 1a, 1b, 1c . . . 1f pressing one of the surfaces of the web paper W are the surfaces of rollers 2a, 2b, 2c . . . 2f fitted in an mutually spaced manner so as to be rotatable at the shaft 3a. Pressing surfaces 1g, 1h, 1i . . . 1k facing the other surface of the web paper are the surfaces of rolls 2g, 2h, 2i . . . 2k fitted in an mutually spaced manner so as to be positioned at the centers of rollers 2a, 2b, 2c, . . . 2f so as to be rotatable at the shaft 3b. 
The paper web width adjustment device (web paper width adjustment device 20) of the related art is a device where the shafts 3a and 3b are supported using eccentric sleeves 4a, 4b, 4c and 4d. The eccentric sleeves 4a, 4b, 4c and 4d are then made to rotate so as to displace the shafts 3a and 3b and the rollers 2a, 2b, 2c . . . 2k collectively fitted to the rollers 2a, 2b, 2c . . . 2k fitted to the shafts 3a and 3b are displaced.
The pressing members (pressing surfaces 1) of related art 1 are made to move collectively towards and away from both surfaces of the paper web by the ripple adjustment means and are pressed against both sides of the paper web while being made to rotate as a result of making contact with the surfaces of the paper web. A ripple effect is therefore generated in a widthwise direction of the paper web, the width of the paper web is adjusted, and there results an action preventing mismatching of printed images.
In related art 1, the pressing members are moved towards and away from the surface of the paper web by the ripple adjustment means so as to make contact and push against the paper web. The pressing member therefore rotates at substantially the same rotational speed as the speed of travel of the paper web in the direction of travel of the paper web in accompaniment with the contact points of the pressing member. Ink printed at a printing unit upstream of the direction of travel of the paper web or specs of paper that have become attached to the paper surface are therefore moved towards the contact parts of the pressing member and deposited due to the rotational displacement of the contact points of the pressing members at substantially the same speed as the paper web. There is therefore a problem that ink and specs of paper deposited at the contact points in this manner subsequently moves to the paper surface of the traveling paper web so as to contaminate the surface of the printing paper.
Further, the contact points of the pressing member are constructed in such a manner that an outer ring to which an inner ring is fixed is rotatable, with a plurality of contact points being provided in the direction of the shafts. The operation of fitting and removing the pressing members to the shafts is therefore not straightforward. In particular, pressing members positioned at the central part of a shaft ride up towards the fitting positions of pressing members further towards the ends of the shafts. Moving as far as a fitting position of a prescribed central portion is therefore necessary which results in a complicated operation.
Further, drive transmitted from the drive source is transmitted to gears that angularly displace integrally with the eccentric sleeves provided at both sides of the pressing members so that the pressing members are moved towards and away from the surfaces of the paper web. It is therefore necessary for the number of gears provided for the drive system to be equal to the number of eccentric sleeves provided on both sides of the pressing member, and initial costs therefore become high.
As the present invention sets out to resolve the aforementioned problems encountered in the related art, it is the object of the present invention to provide a paper web width adjustment device capable of preventing ink or specks of paper from becoming attached to contact parts of pressing members so thus contaminating the surface of the paper web, and to enable straightforward fitting and removing of rotatable pressing members. It is a further object to simplify the transmission mechanism for the ripple adjustment means for moving the pressing members towards and away from the surfaces of the paper web.
In order to resolve the aforementioned problems, it is proposed to provide a paper web width adjustment device comprises: one or more pressing members provided in a rotatable manner for making contact with surfaces of traveling paper web and creating ripples in the paper web and having a plurality of contact points provided integrally so as to be spaced at intervals along the widthwise direction of the paper web;
support shafts for supporting the pressing members in a rotatable manner;
ripple adjustment means capable of moving the support shafts towards and away from the surfaces of the paper web; and
pressing member rotational drive means for, in cooperation with the pressing members, rotatably driving the pressing members,
wherein at least one of the pressing members is capable of moving towards and away from a surface of the paper web, and the rotational speed of the peripheral surfaces of the contact points of the pressing members can be rotatably driven at different speeds to the speed of travel of the paper web.
With the paper web width adjustment device disclosed here, two pressing members are provided facing each other on either side of the paper web.
With the paper web width adjustment device as proposed here, the ripple adjustment means comprises eccentric sleeves fitted in a fixed manner to the ends of the support shafts, and a drive transmission mechanism capable of angularly displacing the eccentric sleeves, being provided in such a manner that central lines of rotation of the pressing members provided in a rotatable manner and the support shafts and central lines of angular displacement of the eccentric sleeves are spaced from each other and are parallel to each other, with the eccentric sleeves being angularly displaced about the center line of angular displacement by the drive transmission means, and with the ripple adjustment means being capable of deciding the positioning of the pressing members with respect to the paper web.
With the paper web width adjustment device as disclosed here, it is proposed that the drive transmission mechanism is equipped with worm wheels provided integrally with the eccentric sleeves in a rotatable manner, worms meshing with the worm wheels, and a rotational drive source for rotationally driving the worms.